Datasheet
Table Of Contents
- Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support
- 1.0 Introduction
- 2.0 Pin Description and Configuration
- 3.0 Functional Description
- 3.1 Transceiver
- 3.2 Auto-negotiation
- 3.3 HP Auto-MDIX Support
- 3.4 MAC Interface
- 3.5 Serial Management Interface (SMI)
- 3.6 Interrupt Management
- 3.7 Configuration Straps
- 3.8 Miscellaneous Functions
- 3.9 Application Diagrams
- 4.0 Register Descriptions
- 4.1 Register Nomenclature
- 4.2 Control and Status Registers
- TABLE 4-2: SMI Register Map
- 4.2.1 Basic Control Register
- 4.2.2 Basic Status Register
- 4.2.3 PHY Identifier 1 Register
- 4.2.4 PHY Identifier 2 Register
- 4.2.5 Auto Negotiation Advertisement Register
- 4.2.6 Auto Negotiation Link Partner Ability Register
- 4.2.7 Auto Negotiation Expansion Register
- 4.2.8 Mode Control/Status Register
- 4.2.9 Special Modes Register
- 4.2.10 Symbol Error Counter Register
- 4.2.11 Special Control/Status Indications Register
- 4.2.12 Interrupt Source Flag Register
- 4.2.13 Interrupt Mask Register
- 4.2.14 PHY Special Control/Status Register
- 5.0 Operational Characteristics
- 6.0 Package Information
- 7.0 Application Notes
- Appendix A: Data Sheet Revision History
- The Microchip Web Site
- Customer Change Notification Service
- Customer Support
- Product Identification System
- Worldwide Sales and Service
2016 Microchip Technology Inc. DS00002165B-page 25
LAN8720A/LAN8720AI
Note 3-1 If the mask bit is enabled and nINT has been de-asserted while ENERGYON is still high, nINT will
assert for 256 ms, approximately one second after ENERGYON goes low when the Cable is
unplugged. To prevent an unexpected assertion of nINT, the ENERGYON interrupt mask should
always be cleared as part of the ENERGYON interrupt service routine.
Note: The ENERGYON bit in the Mode Control/Status Register is defaulted to a ‘1’ at the start of the signal acqui-
sition process, therefore the INT7 bit in the Interrupt Mask Register will also read as a ‘1’ at power-up. If no
signal is present, then both ENERGYON and INT7 will clear within a few milliseconds.
3.6.2 ALTERNATE INTERRUPT SYSTEM
The Alternate interrupt system is enabled by setting the ALTINT bit of the Mode Control/Status Register to “1”. In this
mode, to set an interrupt, set the corresponding bit of the in the Mask Register 30, (see Table 3-4). To Clear an interrupt,
either clear the corresponding bit in the Interrupt Mask Register to deassert the nINT output, or clear the interrupt
source, and write a ‘1’ to the corresponding Interrupt Source Flag. Writing a ‘1’ to the Interrupt Source Flag will cause
the state machine to check the Interrupt Source to determine if the Interrupt Source Flag should clear or stay as a ‘1’. If
the Condition to deassert is true, then the Interrupt Source Flag is cleared and nINT is also deasserted. If the Condition
to deassert is false, then the Interrupt Source Flag remains set, and the nINT remains asserted.
30.5 29.5 Remote Fault
Detected
1.4 Remote Fault Rising 1.4 Falling 1.4, or
Reading register 1 or
Reading register 29
30.4 29.4 Link Down 1.2 Link Status Falling 1.2 Reading register 1 or
Reading register 29
30.3 29.3 Auto-Negotiation
LP Acknowledge
5.14 Acknowledge Rising 5.14 Falling 5.14 or
Read register 29
30.2 29.2 Parallel Detection
Fault
6.4 Parallel Detec-
tion Fault
Rising 6.4 Falling 6.4 or
Reading register 6, or
Reading register 29
or
Re-Auto Negotiate or
Link down
30.1 29.1 Auto-Negotiation
Page Received
6.1 Page Received Rising 6.1 Falling of 6.1 or
Reading register 6, or
Reading register 29
Re-Auto Negotiate, or
Link Down.
TABLE 3-2: INTERRUPT MANAGEMENT TABLE